Arrangement for transmitting current impulses



July 28, 1942. HETTENHAUSEN 2,290,909

ARRANGEMENT FOR TRANSMITTING CURRENT IMPULSES Filed April 21, 1939lnventor:

Ddecf Cal /emf Source Patented July 28, 1942 ARRANGEMENT FORTRANSMITTING CURRENT MPULSES Georg Hettenhausen, Kiel, Germany, assignorto C. Lorenz Aktiengesellschaft, Berlin-Tempelhof, Germany, a companyApplication April 21, 1939, Serial No. 269,101 i In Germany February 12,1938 Claims.

In arrangements in which communications are transmitted by means ofalternating carrier currents it is in some cases necessary also totransmit ringing signals which, for instance, are formed of analternating current of low frequency and produced with the aid of amagneto. 0n the transmitting side a relay is arranged to affect thecarrier frequency in accordance with the ringing frequency. To employ arelay of normal or standard type is not possible, because such a relaywould respond to each half-Wave of the low frequency ringing current,whereby the impulse succession on the carrier frequency side would bedouble that of the low frequency side.

Instead of a non-polarized relay a polarized relay might be employed,because it would then be possible to fulfil the said requirement, ifonly one contact of this relay were used for affecting the carrierfrequency. In this case, however, the disadvantage arises that it willbe unknown on which of the contacts the polarized relay would remainresting, that is, the relay might happen to remain in its ringing state.If, in order to avoid this drawback, an electric or mechanicalunilateral bias voltage were provided, the sensitivity of thearrangement would be impaired thereby.

Therefore, a non-polarized relay and a rectifier connected in advancethereof have been used. The relay in this case only responds to eachsecond half-wave. In the event of a quick impulse succession, however,or with a high sensitivity, the relay in consequence of a great timeconstant determining the release thereof, may happen not to drop itsarmature during the period of no-current. As a result, the ringingfrequency will not be properly transmitted to the receiving side.

In order to overcome this disadvantage, the invention proposes toprovide a resistance connected in parallel with the rectifier which inits turn is arranged in series connection with the said relay. Thisresistance is connected in shunt with the rectifier and is calculated toallow a comparatively small current amplitude to flow through the relay.This current amplitude acts to reverse the polarity of the field in thecore of the relay, that is to say, the core is demagnetized without therelay responding.

Instead of such ohmic resistance a condenser or a resistance-condensercombination may be connected in shunt with the rectifier.

In the accompanying drawing Fig. 1 shows the circuit arrangement of oneembodiment of the invention, while Figs. 2 and 3 represent currentcurves which serve to explain the operation of arrangements as providedby the invention and Fig. 4 shows a modified circuit similar to that ofFig. 1.

The ringing current produced in a subscribers station T by means of amagneto, for instance, and whose current curve I is represented in Fig.2, is transmitted to a carirer frequency apparatus and is employed herefor keying in impulse-fashion the carrier frequency produced bygenerator F. The keying frequency is conveyed to a relay E having acontact e. Connected in advance of relay E is a rectifier G which, inaccordance with the invention, is bridged over by a resistance A, suchas a high ohmic resistance, for instance. In this way the current curve2, Fig. 3, is obtained which enables a proper modulation of the carrierfrequency to be effected by contact e.

As shown in Fig. 4 the element A of Fig. 1 is replaced by a resistance Iand condenser 2 in parallel and source F is shown as a direct currentsource instead of an alternating current source. This modified circuitcan be used in place of that shown in Fig. 1 and will producesubstantially similar results.

The arrangement may be employed also in the case of ringing over lowfrequency talking lines, and it may be employed whenever in the case ofan impulse transmission a contact is desired to be continuously held inits open or closed position.

What is claimed is:

1. An arrangement for converting alternating ringing current intocurrent impulses of equal frequency, comprising a rectifier andresistance in shunt combination, a non-polarized relay connected inseries with said combination to form a series circuit, means forsupplying said alternating ringing current across said series circuitand an impulse producing circuit controlled by said relay.

2. An arrangement according to claim 1, wherein said resistance is anohmic resistance.

3. An arrangement according to claim 1, wherein said resistancecomprises an ohmic resistance and condenser in series.

4. An arrangement according to claim 1, wherein said impulse producingcircuit comprises a course of direct current and means controlled bysaid relay for impressing direct current impulses from said source on asignal line.

5. An arrangement according to claim 1, wherein said impulse producingcircuit comprises a source of carrier frequency and means controlled bysaid relay for impressing carrier frequency impulses from said source onsaid signal line.

, GEORG HE'ITENHAUSEN.

